Thermostats presently used for automobile engines or the like, although they generally serve their intended purpose, are subject to certain disadvantages. First of all, they do not control engine temperature within a sufficiently narrow range to insure efficient engine operation. Secondly, in the event of failure of the thermostat mechanism, the thermostat is closed to prevent the flow of cooling liquid which results in overheating of the engine.
A need has arisen, therefore, for a thermostat that closely controls engine temperature for fuel savings and permits an adequate flow of cooling liquid therethrough to prevent engine overheating in the event of failure of the operating mechanism of the thermostat.